RNA Interference
RNA interference (RNAi) is a phenomenon involving double-stranded (ds) RNA-dependent gene-specific posttranscriptional gene silencing. Originally, attempts to study this phenomenon and to manipulate mammalian cells experimentally were hindered by a non-specific antiviral defense mechanism activated in response to long dsRNA molecules (see Gil et al. Apoptosis 2000, 5:107-114). Later it was discovered that short, synthetic RNA duplexes of 21 nucleotides could mediate gene specific RNAi in mammalian cells, precluding stimulation of the generic antiviral defense mechanisms (see Elbashir et al. Nature 2001, 411:494-498; Caplen et al. PNAS USA 2001, 98:9742-9747). As a result, small interfering RNAs (siRNAs) have become powerful tools in attempting to understand gene function.
RNA interference (RNAi) in mammals is mediated by small interfering RNAs (siRNAs) (Fire et al, Nature 1998, 391:806) or microRNAs (miRNAs) (Ambros, Nature 2004, 431(7006):350-355; Bartel, Cell 2004, 116(2): 281-97). The corresponding process in plants is commonly referred to as specific post-transcriptional gene silencing (PTGS) or RNA silencing and is also referred to as quelling in fungi.
An siRNA is a double-stranded RNA or modified RNA molecule which down-regulates or silences (prevents) the expression of a gene/mRNA of its endogenous (cellular) counterpart. The mechanism of RNA interference is detailed infra.
Several studies have revealed that siRNA therapeutics is effective in vivo in both mammals and in humans. Bitko et al., have shown that specific siRNA molecules directed against the respiratory syncytial virus (RSV) nucleocapsid N gene are effective in treating mice when administered intranasally (Nat. Med. 2005, 11(1):50-55). Recent reviews discussing siRNA therapeutics are available (Barik, et al., J. Mol. Med. 2005, 83:764-773; Dallas and Vlassov, Med. Sci. Monitor 2006, 12(4):RA67-74; Chakraborty Current Drug Targets 2007, 8(3):469-82).
Mucke (IDrugs 2007 10(1):37-41) presents a review of current therapeutics, including siRNA to various targets, for the treatment of ocular diseases, for example age related macular degeneration (AMD) and glaucoma.
Pro-Apoptotic Genes
Pro-apoptotic genes are genes that encode proteins that play a role in apoptotic cell death. A non-limiting list of pro-apoptotic genes used in the present invention are: tumor protein p53 (P53 or TP53 which terms are used herein interchangeably); HtrA serine peptidase 2 (HTRA2); Kelch-like ECH associated protein 1 (KEAP1); Src homology 2 domain containing transforming protein 1 (SHC1-SHC, p66); zinc finger HIT type (ZNHIT1); lectin galactose-binding soluble 3 (LGALS3); and sestrin2 (HI95, SESN2).
Inhibition of one or more of the above genes is useful in the treatment and/or prevention of at least one of the following diseases or disorders and of other diseases disclosed herein: hearing loss, in particular chemical-induced ototoxicity, acute renal failure (ARF), chronic obstructive pulmonary disease (COPD), ischemia reperfusion injury following lung transplantation, lung cancer, acute respiratory disease syndrome (ARDS), spinal cord injury, pressure sores, osteoarthritis, diabetic retinopathy, oral mucositis, dry eye syndrome, ocular ischemic conditions and injury associated with organ transplant. The function of HI95 has been disclosed in Budanov et al., 2002, 21(39):6017-31.
Hearing Loss: Chemical-Induced Ototoxicity
The ototoxic effects of various therapeutic drugs on auditory cells and spiral ganglion neurons are often the limiting factor for their therapeutic usefulness. Main ototoxic drugs include the widely used chemotherapeutic agent cisplatin and its analogs, commonly used aminoglycoside antibiotics, e.g. gentamycin, for the treatment of infections caused by gram-negative bacteria, quinine and its analogs, salicylate and its analogs, and loop-diuretics.
For example, antibacterial aminoglycosides such as gentamycins, streptomycins, kanamycins, tobramycins, and the like are known to have serious toxicity, particularly ototoxicity and nephrotoxicity, which reduce the value of such antimicrobials as therapeutic agents (see Goodman and Gilman's The Pharmacological Basis of Therapeutics, 6th ed., A. Goodman Gilman et al., eds; Macmillan Publishing Co., Inc., New York, 1980, pp. 1169-71).
Ototoxicity is a dose-limiting side-effect of antibiotic administration and of cisplatin, a platinum coordination complex, that has proven effective on a variety of human cancers including testicular, ovarian, bladder, and head and neck cancer. Platinum based drugs include carboplatin, cisplatin, oxaliplatin and satrapaltin inter alia; (see Kelland and Farrell eds., Platinum-based drugs in cancer therapy Human Press 2000; which is hereby incorporated by reference).
Cisplatin (Platinol®) and cisplatin-like compounds (platinum based compounds) damage auditory and vestibular systems.
Salicylates, such as aspirin, are the most commonly used therapeutic drugs for their anti-inflammatory, analgesic, anti-pyretic and anti-thrombotic effects. Unfortunately, they too have ototoxic side effects and can lead to tinnitus (“ringing in the ears”) and temporary hearing loss. Moreover, if the drug is used at high doses for a prolonged time, chronic and irreversible hearing impairment can arise.
Without being bound by theory, it is believed that cisplatin drugs (cisplatin and cisplatin-like compounds) and other potentially ototoxic drugs (such as aminoglycoside antibiotics) may induce the ototoxic effects via programmed cell death or apoptosis in inner ear tissue, particularly inner ear hair cells (Mang et al., Neuroscience 2003, 120(1):191-205; Wang et al., J. Neuroscience 2003, 23(24):8596-8607). Presbycusis, age related hearing loss, is prevalent in the aging population with about 30-35 percent of adults between the ages of 65 and 75 years and about 40-50 percent of people aged 75 and older affected.
In mammals, auditory hair cells are produced only during embryonic development and do not regenerate if lost during postnatal life, therefore, loss of hair cells results in profound and irreversible deafness. Unfortunately, at present, there are no effective therapies to treat the cochlea and reverse this condition. Thus, an effective therapy to prevent cell death of auditory hair cells would be of great therapeutic value.
Accordingly, there exists a need for means to prevent, reduce or treat the incidence and/or severity diseases or disorders resulting from chemical toxicity including inner ear disorders and hearing impairment, renal damage (nephrotoxicity) and neural damage (neurotoxicity
Acute Renal Failure
Acute renal failure (ARF) is a clinical syndrome characterized by rapid deterioration of renal function that occurs within days. The principal feature of ARF is an abrupt decline in glomerular filtration rate (GFR), resulting in the retention of nitrogenous wastes (urea, creatinine). Worldwide, severe ARF occurs in about 170-200 per million population annually. To date, there is no specific treatment for established ARF. Several drugs have been found to ameliorate toxic and ischemic experimental ARF, as manifested by lower serum creatinine levels, reduced histological damage and faster recovery of renal function in different animal models. These include anti-oxidants, calcium channel blockers, diuretics, vasoactive substances, growth factors, anti-inflammatory agents and more. However, the drugs tested in clinical trials showed no benefit, and their use in clinical ARF has not been approved.
In the majority of hospitalized ARF patients, ARF is caused by acute tubular necrosis (ATN), which results from ischemic and/or nephrotoxic insults. Renal hypoperfusion is caused by hypovolemic, cardiogenic and septic shock, by administration of vasoconstrictive drugs, renovascular injury or kidney transplant. Nephrotoxins include exogenous toxins such as contrast media, aminoglycosides and cisplatin and cisplatin-like compounds as well as endogenous toxin such as myoglobin. Any chemical, biological or other agent which causes ARF or other kidney disease or disorder may be considered a nephrotoxin. Recent studies, however, support the theory that apoptosis in renal tissues is prominent in most human cases of ARF. The principal site of apoptotic cell death is the distal nephron. During the initial phase of ischemic injury, loss of integrity of the actin cytoskeleton leads to flattening of the epithelium, with loss of the brush border, loss of focal cell contacts, and subsequent disengagement of the cell from the underlying substratum. It has been suggested that apoptotic tubule cell death may be more predictive of functional changes than necrotic cell death (Komarov et al., Science 1999, 10; 285(5434):1733-7); Supavekin et al., Kidney Int. 2003, 63(5):1714-24).
In conclusion, currently there are no satisfactory modes of therapy for the prevention and/or treatment of acute renal failure, and there is a need therefore to develop novel compounds for this purpose.
Glaucoma
Glaucoma is one of the leading causes of blindness in the world. It affects approximately 66.8 million people worldwide and at least 12,000 Americans are blinded by this disease each year (Kahn and Milton, Am J. Epidemiol. 1980, 111(6):769-76). Glaucoma is characterized by the degeneration of axons in the optic nerve head, primarily due to elevated intraocular pressure (IOP). One of the most common forms of glaucoma, known as primary open-angle glaucoma (POAG), results from the increased resistance of aqueous humor outflow in the trabecular meshwork (TM), causing IOP elevation and eventual optic nerve damage.
Acute Respiratory Distress Syndrome
Acute respiratory distress syndrome (ARDS), also known as respiratory distress syndrome (RDS) or adult respiratory distress syndrome (in contrast with infant respiratory distress syndrome, IRDS) is a serious reaction to various forms of injuries to the lung. This is the most important disorder resulting in increased permeability pulmonary edema.
ARDS is a severe lung disease caused by a variety of direct and indirect insults. It is characterized by inflammation of the lung parenchyma leading to impaired gas exchange with concomitant systemic release of inflammatory mediators causing inflammation, hypoxemia and frequently resulting in multiple organ failure. This condition is life threatening, usually requiring mechanical ventilation and admission to an intensive care unit. A less severe form is called acute lung injury (ALI).
Spinal Cord Injury
Spinal cord injury or myelopathy, is a disturbance of the spinal cord that results in loss of sensation and/or mobility. The two common types of spinal cord injury are due to trauma and disease. Traumatic injury can be due to automobile accidents, falls, gunshot, diving accidents inter alia. and Diseases which can affect the spinal cord include polio, spina bifida, tumors and Friedreich's ataxia.
Ischemia Reperfusion Injury Following Lung Transplantation
Lung transplantation, the only definitive therapy for many patients with end stage lung disease, has poor survival rates in all solid allograft recipients. Ischemia reperfusion (IR) injury is one of the leading causes of death in lung allograft recipients.
Oral Mucositis
Oral mucositis, also referred to as a stomatitis, is a common and debilitating side effect of chemotherapy and radiotherapy regimens, which manifests itself as erythema and painful ulcerative lesions of the mouth and throat. Routine activities such as eating, drinking, swallowing, and talking may be difficult or impossible for subjects with severe oral mucositis. Palliative therapy includes administration of analgesics and topical rinses.
Dry Eye Syndrome
Dry eyes and dry eye syndrome are common problems usually resulting from a decrease in the production of tear film that lubricates the eyes. Most patients with dry eye experience discomfort, and no vision loss; although in severe cases, the cornea may become damaged or infected. Wetting drops (artificial tears) may be used for treatment while lubricating ointments may help more severe cases. Dry eyes is a hallmark symptom of Sjogren's syndrome.
Ocular Ischemic Conditions
Ischemic optic neuropathy (ION) includes a variety of disorders that produce ischemia to the optic nerve. By definition, ION is termed anterior if disc edema is present acutely, suggesting infarction of the portion of the optic nerve closest to the globe. ION also may be posterior, lying several centimeters behind the globe. Ischemic optic neuropathy usually occurs only in people older than 60 years of age. Most cases are nonarteritic and attributed to the effects of atherosclerosis, diabetes, or hypertension on optic nerve perfusion. Temporal arteritis causes about 5% of cases (arteritic ION).
Symptoms and signs are sudden, partial or complete vision loss, accompanied by swelling of the optic nerve head and often hemorrhage. Visual field defects may manifest as loss of half the visual field with a horizontal demarcation or as central or centrocecal (surrounding the natural blind spot) scotomata. Decreased vision is soon followed by pallor of the optic disk.
International patent application WO 00/44364 discloses TP53 inhibitors and their use for treatment of many diseases. International patent application no. WO 2006/035434 assigned to the assignee of the present invention discloses TP53 inhibitors for the treatment of, inter alia, acute renal failure and hearing loss). U.S. Pat. No. 7,074,895 assigned to the assignee of the present invention teaches full length HI95 polypeptide. GB 2420119 discloses certain KEAP1 siRNA. WO 03/087368 and WO 03/087367 teach methods of treating various eye and CNS diseases with RNAi to various target genes.
An effective therapy to treat the above mentioned diseases and disorders would be of great therapeutic value.